The manufacture of semiconductor integrated circuits has become a competitive, high volume commodity business. As such, controlling the cost of each completed circuit improves the commercial effectiveness of that circuit. For the semiconductor manufacturing industry, the time necessary to complete each manufacturing step has a direct relationship and effect on the cost of that circuit. One time-consuming phase during the fabrication of semiconductor devices is singulation. Singulation is a process for dicing a sheet of fabricated semiconductor die and/or packages into individual units. Semiconductor dice are typically mass produced on a wafer and good dice are mounted on a leadframe. The leadframes are also typically mass produced in large batches by the sheet. Depending on the manufacturing process, the sheet of leadframes can have an adhesive (dicing) tape applied to one side of the sheet before an encapsulation is applied to the dice mounted on the leadframes. The encapsulation is typically performed by molding a plastic resin to the sheet of dice and leadframes. In these cases, the dicing tape provides a lower support structure for the formation of the plastic molding during encapsulation. The encapsulation is commonly referred to as a semiconductor package.
A singulation process separates each package from the molded sheet. The molded sheet is typically divided into molded strips for singulation. There are various techniques currently being practiced for singulation. One technique involves punching, while another technique involves sawing the molded strip to separate the packages from the molded strip. Two particular drawbacks related to sawing the molded strip are (1) lengthy singulation times and (2) defects in the singulated product. Both drawbacks are related to the heat generated by the singulation blade. The saw blade cuts the resin and can cut the lead frame into a plurality of particles. While cutting, the blade forms a well-known trench-like kerf. The kerf can fill with particles which can bind between the blade and a wall of the kerf. The particles can damage the wall of the kerf leading to failures or reliability problems.
The conventional method for singulating semiconductor packages uses a dicing saw having a saw blade which is typically very thin (approximately 0.2 mm-0.3 mm) and which rotates at a very high speed. Jets of fluid directed at the saw blade to cool it as it cuts the substrate have the unintended effect of easily deflecting the thin cutting blade when the jets of fluid impacting outwardly opposing sides of the cutting blade are misaligned. This is caused by the imbalance in forces created by the misaligned fluid jets impacting the saw blade on either of its side. The higher the cutting rate is desired, the higher the rate of discharge of fluid is needed to cool the blade. However, under the conventional method the higher the rate of discharge of fluid, the greater the effect of imbalanced impact of forces on either side of the blade results. This in turn causes the cutting blade to vibrate due to dynamic imbalance when the saw blade rotates at a very high speed which in turns lead to inefficient cutting thus constraining cutting speeds and the attainment of quality cuts.
FIG. 1 through FIG. 4A shows a conventional cooling system comprising a discharge apparatus 100 having two pipes 102 for receiving fluid through an interface 130, a center blade cooling nozzle 110, and a cutting blade 106 (FIG. 1). The apparatus uses water or a chemical coolant in order to transfer heat and also to lubricate at a cutting area. FIGS. 2 and 2A show holes 104 formed along a portion of each of the two pipes for discharging the fluid. The cutting blade 106 is typically displaced between the two pipes 102 with the holes 104 of each of the two pipes 102 facing a portion of the cutting blade 106, while a hole 112 (FIG. 4A) of the center blade cooling nozzle 110 faces towards the cutting blade 106 and the cutting area for discharging the fluid onto the cutting blade for cooling thereof. The holes 104 direct fluid in a trapezoidal shape 108 and the hole 112 directs fluid in a cone shaped spray 114 both because of substantial dispersion of fluid fail to sufficiently direct cooling fluid at the cutting area. Further, the present apparatus 100 fails to efficiently remove debris from the cutting area. Also, to direct the discharged fluid onto the cutting blade 106, the holes 104 on the two pipes 102 are manually positioned by hand-bending the two pipes 102. However, hand-bending of the two pipes 102 is an inaccurate and crude manner for aligning the holes 104. Additionally, hand-bending of the two pipes 102 may lead to fracturing of either of the two pipes 102.
Accordingly, there is a need to accelerate the singulation process without negatively affecting quality or reliability of the singulated product and improve an apparatus for directing fluid at the cutting blades.